In conventional fuel delivery systems for internal combustion engines, a constant-delivery fuel pump supplies fuel under pressure from a tank to a fuel rail positioned on the engine. Excess fuel is returned to the supply tank by a pressure regulator coupled to the fuel rail for maintaining substantially constant fuel pressure within the fuel rail. A plurality of fuel injectors are mounted between the fuel rail and the engine intake manifold, with the injector nozzles being positioned adjacent to the fuel/air intake ports of the individual engine cylinders. The fuel injectors are individually electromagnetically actuated by an engine control unit as a function of operating conditions and parameters at the engine.
A major cost associated with fuel delivery systems of the described character lies in the individual fuel injectors, and in the complexity of electrical conductors that connect the fuel injectors to the engine control unit. The fuel injectors are subject to wear, and may eventually feed differing quantities of fuel to the cylinders even when actuated for nominally identical time durations, thus resulting in less than optimum engine operation. Furthermore, conventional fuel injectors present additional difficulties when employed in conjunction with so-called alternative fuels. Fuels of this character have lower lubricity than conventional gasoline fuels, increasing wear at the individual injectors. The injector wear parts may be constructed of stainless steel, for example, which reduces wear but greatly increases cost. Moreover, because of lower energy content of alcohol-based alternative fuels, for example, the injectors must have a larger fuel opening and/or remain open longer than would otherwise be desirable in operation with gasoline. Thus, conventional fuel injectors are not well suited for use in association with engines intended for operation with alternative fuels having differing potential energy contents.
A general object of the present invention is to provide a fuel delivery system for internal combustion engines in which conventional electromagnetic fuel injectors are eliminated, thereby achieving reduced cost, reduced complexity, reduced wear and increased operating life as compared with conventional systems of the character described above. Another and related object of the present invention is to provide a fuel delivery system in which identical quantities of fuel are automatically delivered to all of the engine cylinders, and in which fuel quantity may be automatically controlled over a wide flow range for uses in conjunction with multiple fuel types without requiring adjustment by an operator or engine technician.